The invention relates to balloon catheters adapted for introduction into passageways and organs of the body. The catheter is typically introduced with the balloon in deflated condition for ease of insertion and to minimize the size of the opening required. Once in the desired position, the balloon is inflated by introducing fluid, i.e., liquid or gas, through the lumen of the catheter into the balloon.
In certain procedures, particularly where escape of inflating fluid within the body, e.g., due to perforation of the balloon, could adversely affect a patient's health, the fluid is carefully selected. An example is coronary angioplasty, a procedure for enlarging the flow diameter of arteries of the heart involving repeated inflation and deflation of a low profile dilatation balloon. Saline or contrast media is used as the inflating fluid because introduction of gas into the coronary arteries could be fatal. During filling of the balloon and catheter prior to commencing the procedure, all gas must be vented from the device. Samson (1986, U.S. Pat. No. 4,582,181, not conceded to be prior art to this application) uses a hypodermic tube inserted from the proximal end of the catheter to vent the air during initial filling of the system with saline or contrast media.
The objectives of this invention include providing a balloon constructed to selectively vent gas during filling with inflation fluid; providing such a balloon that may be vented without need for accessory items; providing such a balloon which can vented and prepared for insertion in much reduced time as compared to prior art devices; providing a balloon catheter of such construction, having a balloon of low profile and catheter of relatively small diameter; and providing such a balloon catheter suitable for coronary angioplasty.